US4257274A - Capacitive pressure sensor - Google Patents
Capacitive pressure sensor Download PDFInfo
- Publication number
- US4257274A US4257274A US06/059,552 US5955279A US4257274A US 4257274 A US4257274 A US 4257274A US 5955279 A US5955279 A US 5955279A US 4257274 A US4257274 A US 4257274A
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- Prior art keywords
- diaphragm
- substrate
- pressure sensor
- thin
- conductive silicon
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L13/00—Devices or apparatus for measuring differences of two or more fluid pressure values
- G01L13/02—Devices or apparatus for measuring differences of two or more fluid pressure values using elastically-deformable members or pistons as sensing elements
- G01L13/025—Devices or apparatus for measuring differences of two or more fluid pressure values using elastically-deformable members or pistons as sensing elements using diaphragms
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
- G01L9/0041—Transmitting or indicating the displacement of flexible diaphragms
- G01L9/0042—Constructional details associated with semiconductive diaphragm sensors, e.g. etching, or constructional details of non-semiconductive diaphragms
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
- G01L9/0041—Transmitting or indicating the displacement of flexible diaphragms
- G01L9/0072—Transmitting or indicating the displacement of flexible diaphragms using variations in capacitance
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
- G01L9/0041—Transmitting or indicating the displacement of flexible diaphragms
- G01L9/0072—Transmitting or indicating the displacement of flexible diaphragms using variations in capacitance
- G01L9/0073—Transmitting or indicating the displacement of flexible diaphragms using variations in capacitance using a semiconductive diaphragm
Definitions
- FIG. 4 is a sectional view showing another embodiment of the capacitive pressure sensor according to this invention.
- FIG. 9 is a sectional view showing still another embodiment of the capacitive pressure sensor according to this invention.
- the whole structure is heated to a temperature of about 450° C., and a high voltage of about 1,000 volts (V) is applied across the electrodes for several minutes.
- V 1,000 volts
- the bonded surfaces between the silicon diaphragm 203 and the glass substrates 201a and 201b are electrostatically joined, and they never separate even when the voltage is removed.
- the diaphragm and the substrates can be joined under the ideal state of high strength and no distortion without employing any binder. For this reason, the linearity in the pressure transduction characteristic of the capacitive pressure sensor having the above construction is enhanced.
- a plurality of capacitive pressure sensors can be assembled at a time by placing the glass substrates on a silicon wafer in which a plurality of diaphragms are formed. Therefore, the productivity is also enhanced.
- the thin portion 206 of the diaphragm is formed.
- the heavily doped layers 210a and 210b are approximately ten times higher in the etching rate than the silicon substrate 203 of low impurity density, so that the silicon substrate 203 can be left as the thin movable portion 206 of the diaphragm at a uniform thickness.
- the oxide films 211a and 211b are removed to obtain the silicon diaphragm 203.
- the external shape of the silicon diaphragm 203 to be fabricated by such process and the shape of the movable portion 206 can be made shapes convenient for design at will.
- the spacers 310a and 310b are stacked with the silicon diaphragm 203 intervening therebetween, and the silicon substrates 300a and 300b are placed on both the sides of the resultant structure.
- a negative electrode is attached to the insulator or the ring-shaped spacers 310a and 310b made of the glass, while a positive electrode is attached to the conductors or the silicon diaphragm 203 and the silicon substrates 300a and 300b.
- the resultant structure is heated to a temperature of approximately 450° C., and a high voltage of approximately 1,000 volts (V) is applied across the electrodes for several minutes.
- V 1,000 volts
Abstract
A capacitive pressure sensor is provided which has a conductive silicon diaphragm having a thick supporting portion at the periphery thereof and a thin inner deflecting portion which is reduced in thickness from the supporting portion by means of an etching process which makes possible a very accurate dimensioning of the hollow formed by the deflecting portion of the diaphragm. A substrate of borosilicate glass has a flat surface which is placed against the side of the diaphragm in contact with the supporting portion and the two elements are joined by a process of anodic bonding so that a pressure chamber is formed between the substrate and the thin deflecting portion of the diaphragm. Within the pressure chamber, a thin electrode is provided on the surface of the substrate thereby forming electrostatic capacity between the substrate and the diaphragm and a hole is provided through the substrate for supplying of fluid into the pressure chamber.
Description
This invention relates to a pressure sensor, and more particularly to a capacitive pressure sensor which detects the deviation of a diaphragm responsive to a pressure in the form of a change in an electrostatic capacity.
As disclosed in, for example, U.S. Pat. No. 3,232,114, a capacitive pressure sensor has heretofore been provided in which a resilient diaphragm is formed of metal under uniform tension. It is required of the capacitive pressure sensor that the proportionality (linearity) between the input pressure and the output voltage is high. For meeting this requirement, it is a very important factor that the diaphragm is formed under uniform tension. In the disclosure of the above patent, the diaphragm is maintained under a stress of approximately 60,000 pounds, and its marginal portion is disposed between and is welded to two metal housing sections. The diaphragm, for the above reasons, must be carefully welded to the two housing sections while in stressed condition. Such a process has been carried out with, for example, arc welding or electron-beam welding. However, it has been very difficult to fix the diaphragm under the high tension and uniform state, resulting in the disadvantage of low productivity.
In U.S. Pat. No. 3,793,885, there is disclosed a diaphragm construction for a capacitive pressure transducer in which the measuring components, particularly a pressure-deformable diaphragm, are constructed from a brittle material, such as fused quartz, to take advantage of low hysteresis and creep factors and a low thermal coefficient of expansion. However, the brittle materials disclosed in this patent are insulators, and a conductor must be evaporated onto the surface of the pressure-deformable diaphragm formed of the insulator. In addition, the shape of the diaphragm is cylindrical.
Various techniques for joining elements are also known in the art; for example, U.S. Pat. No. 3,397,278 discloses an anodic bonding technique.
It is therefore an object of this invention to provide a capacitive pressure sensor which does not require a difficult welding process as in the prior art, that is, which has a structure which is easy to fabricate.
Another object of this invention is to provide a capacitive pressure sensor which has a novel diaphragm having excellent characteristics.
Still another object of this invention is to provide a capacitive pressure sensor which is excellent in various characteristics and small in size.
This is accomplished by employing the anodic bonding technique in the step of bonding a diaphragm formed of a conductor onto a substrate formed of an insulator.
Excellent characteristics are also accomplished by forming the diaphragm of the capacitive pressure sensor by the use of silicon.
Finally, in accordance with the invention, the diaphragm is formed of silicon which is excellent in workability, while the substrate is formed of borosilicate glass which is substantially equal to silicon in the coefficient of thermal expansion, and that the silicon diaphragm and the substrate made of borosilicate glass are joined by the anodic bonding technique. The diaphgram itself is formed of an outer thick supporting portion and an inner thin deflecting portion so that in combination with the substrate a hollow pressure chamber is provided.
The above objects and other objects and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments given with reference to the accompanying drawings.
FIG. 1 is a perspective view, partially in section, of a differential pressure transmitter for industrial use which employs an embodiment of the capacitive pressure sensor according to this invention;
FIG. 2 is an enlarged sectional view of the capacitive pressure sensor shown in FIG. 1;
FIGS. 3(a) to 3(d) are views for explaining a manufacturing process for a silicon diaphragm shown in FIG. 1 or FIG. 2;
FIG. 4 is a sectional view showing another embodiment of the capacitive pressure sensor according to this invention;
FIGS. 5 and 6 are sectional views each showing another embodiment of the capacitive pressure sensor according to this invention which has a diaphragm of different shape;
FIG. 7 is a perspective view, partially in section, for elucidating the diaphragms of different shapes shown in FIGS. 5 and 6;
FIGS. 8(a) to 8(e) are views for explaining a manufacturing process for still another diaphragm; and
FIG. 9 is a sectional view showing still another embodiment of the capacitive pressure sensor according to this invention.
Referring to FIG. 1, a differential pressure transmitter for industrial use has housings 1a and 1b in which a capacitive pressure sensor, more exactly, differential pressure sensor 2 according to this invention is assembled, and two end caps 3a and 3b which are placed on respective sides of the housings. Both the housings 1a and 1b and the two end caps 3a and 3b are formed by, for example, the die casting of a metal such as aluminum, and they are rigidly secured to each other by, for example, welding or screws.
The respective sides of the housings 1a and 1b are formed with circular recesses 11a and 11b, which define spaces along with recesses 31a and 31b of the end caps 3a and 3b, respectively. The respective end caps 3a and 3b have pressure inlets 32a and 32b, through which external fluids under respective pressures to be measured are led into the spaces inside the pressure transmitter.
Referring also to FIG. 2, the capacitive differential pressure sensor 2 has substrates 201a and 201b which are formed of an insulating material and which have metallic thin film electrodes 202a and 202b attached to their inner surfaces, respectively, and a diaphragm 203 which is sandwiched between the two substrates 201a and 201b. The substrates 201a and 201b are respectively formed with pressure introducing apertures 204a and 204b at positions corresponding to the pressure conduits 14a and 14b, and through the pressure conduits 14a and 14b as well as the pressure introducing apertures 204a and 204b, the silicone oils 13a and 13b enclosed in the interspaces are led into pressure chambers 205a and 205b defined between the substrates 201a and 201b and the diaphragm 203, respectively. The diaphragm 203 is made up of a thin-walled movable portion 206 and a thick-walled fixed portion 207. The electrodes 202a and 202b are respectively led to the lead wires 21 and 23 through lead wires 208a and 208b which are buried in the substrates 201a and 201b. A three-layered electrode or an aluminum electrode, for example, is formed on the diaphragm 203, and the lead wire 22 is connected therewith.
In this embodiment, both the substrates 201a and 201b are formed of borosilicate glass, while the diaphragm 203 is formed of silicon. Such silicon diaphragm 203 has the advantage that the various characteristics thereof as a diaphragm are excellent owing to low hysteresis and creep factors. Besides, it has the advantage that a precise and distortionless working can be made by, for example, etching, especially a superprecision working in the order of microns being possible with the alkali etching technique. Since the silicon can also be used as a conductor by adjusting the impurity density thereof, it becomes unnecessary to form a thin film electrode of a metal or the like on the surface of the silicon. The borosilicate glass forming the substrate has a coefficient of thermal expansion of 3.25×10-6 /°C., which is approximately equal to the coefficient of thermal expansion of the silicon, so that any distortion is not caused by a change in the ambient temperature.
An example of a method of fabricating the capacitive differential pressure sensor will now be described. A metal of high conductivity such as gold (Au) and platinum (Pt) is evaporated or plated onto the inner surfaces of the substrates 201a and 201b, to form the thin film electrodes 202a and 202b. Thereafter, the silicon diaphragm 203 is sandwiched in between these substrates 201a and 201b. A positive electrode is attached to the conductor, i.e., silicon diaphragm 203, while a negative electrode is attached to the insulator, i.e., glass substrates 201a and 201b. Subsequently, the whole structure is heated to a temperature of about 450° C., and a high voltage of about 1,000 volts (V) is applied across the electrodes for several minutes. In consequence, the bonded surfaces between the silicon diaphragm 203 and the glass substrates 201a and 201b are electrostatically joined, and they never separate even when the voltage is removed. Owing to such anodic bonding technique, the diaphragm and the substrates can be joined under the ideal state of high strength and no distortion without employing any binder. For this reason, the linearity in the pressure transduction characteristic of the capacitive pressure sensor having the above construction is enhanced. According to such process, a plurality of capacitive pressure sensors can be assembled at a time by placing the glass substrates on a silicon wafer in which a plurality of diaphragms are formed. Therefore, the productivity is also enhanced.
FIGS. 3(a) to 3(d) illustrates a method of fabricating the silicon diaphragm 203 shown in FIG. 1 or FIG. 2. First of all, as shown in FIG. 3(a), layers 210a and 210b in which, for example, boron is diffused at a high density of 1024 atoms/cm3 are formed in both the surfaces of the silicon substrate 203. As shown in FIG. 3(b), oxide films 211a and 211b formed at this time are partly removed with the photoetching. Subsequently, as shown in FIG. 3(c), the heavily doped layers are removed by acid etching, alkali etching or the like by employing the remaining oxide films 211a and 211b as a mask. Thus, the thin portion 206 of the diaphragm is formed. The heavily doped layers 210a and 210b are approximately ten times higher in the etching rate than the silicon substrate 203 of low impurity density, so that the silicon substrate 203 can be left as the thin movable portion 206 of the diaphragm at a uniform thickness. Thereafter, as shown in FIG. 3(d), the oxide films 211a and 211b are removed to obtain the silicon diaphragm 203. The external shape of the silicon diaphragm 203 to be fabricated by such process and the shape of the movable portion 206 can be made shapes convenient for design at will.
With the capacitive differential pressure sensor 2 as stated above, the movable portion 206 of the diaphragm 203 is deflected depending upon the difference of the pressures of the fluids or silicon oils 13a and 13b respectively introduced into the pressure chambers 205a and 205b through the pressure introducing apertures 204a and 204b in both the side surfaces of the pressure sensor, the distances between the diaphragm 203 and the respective electrodes 202a and 202b are accordingly varied, and an output voltage Eo expressed by the following equations is provided by an electric circuit not shown: ##EQU1## In the above equations, Cs denotes a reference capacitance, Es the output A.C. voltage of an oscillator in the electric circuit, ε a dielectric constant, A the area of the electrodes, Xo an initial clearance, and X the deflection of the diaphragm.
FIG. 4 shows a capacitive pressure sensor constructed of a diaphragm 203 and a substrate 300a as well as 300b both of which are formed of silicon. Ring-shaped spacers 310a and 310b formed of borosilicate glass are disposed between the silicon diaphragm 203 and the silicon substrates 300a and 300b, to electrically insulate the diaphragm 203 and the substrates 300a and 300b. References 320a and 320b indicate pressure introducing apertures which are respectively formed in the silicon substrates 300a and 300b.
A method of fabricating the above capacitive pressure sensor will now be explained. The spacers 310a and 310b are stacked with the silicon diaphragm 203 intervening therebetween, and the silicon substrates 300a and 300b are placed on both the sides of the resultant structure. A negative electrode is attached to the insulator or the ring-shaped spacers 310a and 310b made of the glass, while a positive electrode is attached to the conductors or the silicon diaphragm 203 and the silicon substrates 300a and 300b. The resultant structure is heated to a temperature of approximately 450° C., and a high voltage of approximately 1,000 volts (V) is applied across the electrodes for several minutes. As a result, the silicon diaphragm 203, the ring-shaped spacers 310a and 310b and the silicon substrates 300a and 300b are firmly joined by the anodic bonding.
Since, in the above embodiment, the substrate 300 is formed of the conductor or silicon, it is unnecessary to evaporate a thin film electrode of a metal or to embed a lead wire in a glass substrate, and a lead wire can be easily taken out by forming a three-layered electrode or an aluminum electrode on the silicon substrate. Therefore, the embodiment can be fabricated more simply.
Each of FIGS. 5 and 6 shows another embodiment of the capacitive pressure sensor or differential pressure sensor according to this invention as has a diaphragm 250 the shape of which is different from that of the diaphragm shown in FIG. 1 or FIG. 2. As also shown in FIG. 7, this diaphragm 250 is made up of a thick fixed portion 251 at its peripheral part, an annular and thin movable portion 252, and a thick electrode portion 253 surrounded by the movable portion. With such diaphragm 250, only the thin movable portion 252 is deflected in response to the pressure, and the thick electrode portion 253 is not deflected by the pressure. Therefore, the surfaces of the electrode portion 252 of the diaphragm 250 and the surfaces of the electrodes disposed on the inner surfaces of the two substrates are parallel at all times. It is also recognized experimentally that the linearity of displacements of the diaphragm in such shape by pressures is excellent. Also such diaphragm can be readily fabricated by etching the silicon with the same method as illustrated in FIGS. 3(a) to 3(d). The external shape of the diaphragm 250 shown in FIG. 7 is square and the shape of the thin movable portion 252 thereof is circular, but these shapes can of course be set as desired.
In the embodiment shown in FIG. 5, the diaphragm 250 is firmly joined between the two substrates 201a and 201b formed of borosilicate glass by the anodic bonding technique already stated. The metallic thin film electrodes 202a and 202b are mounted on the inner surfaces of the respective glass substrates 201a and 201b, and the pressure introducing apertures 204a and 204b are formed in the respective substrates.
In the embodiment shown in FIG. 6, the ring-shaped spacers 310a and 310b and further the substrates 300a and 300b formed of silicon are stacked on both the sides of the diaphragm 250, and they are rigidly joined by the anodic bonding technique. Shown at 320a and 320b are the pressure introducing apertures which are respectively formed in the silicon substrates 300a and 300b.
FIGS. 8(a) to 8(e) illustrate a process for manufacturing a silicon diaphragm by utilizing an oxide film as a stopper. First, oxide films 401a and 401b are formed on both the surfaces of a silicon substrate 400 by the C.V.D. process. Polycrystalline silicon layers 402a and 402b are stacked on the respective oxide films 401a and 401b by epitaxial growth, and are baked up at a high temperature of about 1,000° C. Oxide films formed at this time are partly removed, whereupon using the remaining oxide films 403a and 403b as a mask, the stacked polycrystalline silicon layers 402a and 402b are removed by acid etching or the like so as to form a thin movable portion 404. The oxide films left behind are removed. The thickness of the thin movable portion 404 of the diaphragm fabricated by such process is very uniform, and has a good reproducibility.
Thus far, the differential pressure sensors for detecting the difference of two pressures to be measured have been chiefly explained. However, this invention is also applicable to a pressure sensor for detecting one pressure to be measured as shown in FIG. 9. Referring to the figure, only one side is formed with a recess so as to construct a thin movable portion 501. A silicon diaphragm 500 is placed on a substrate 503 formed of silicon through a spacer 502 made of an insulator, for example, borosilicate glass, and they are rigidly secured by the anodic bonding technique already stated. The substrate 503 is formed with a pressure introducing aperture 504, through which an external fluid under the pressure to be measured is introduced into a pressure chamber defined between the substrate 503 and the diaphragm 500. The pressure sensor of such structure is especially suitable as a small-sized and inexpensive pressure sensor such as negative pressure sensor for automobiles.
Although only the borosilicate glass has thus far been mentioned as the material of the insulating substrate or the insulator spacer, it is also possible to use any of quartz, soft glass, sapphire, etc. The following table lists examples of conditions for joining the materials to the silicon diaphragm by the anodic bonding technique:
______________________________________ Temper- Insulating Time ature material Current density (μA/mm.sup.2) (min.) (°C.) ______________________________________ borosilicate glass 10 20 400 quartz 10 1 900 4 4 soft glass 5 4 450 sapphire 1 1 650 ______________________________________
Regarding the silicon to form the diaphragm or the substrate, either polycrystalline silicon or single-crystal silicon can be employed. In view of experiments, however, the single-crystal silicon is more desirable.
While we have shown and described embodiments in accordance with the present invention, it is understood that the same is not limited thereto but is susceptible to numerous changes and modifications as are obvious to those of ordinary skill in the art, and applicants, therefore, do not wish to be limited to the details described and shown herein but intended to cover all such changes and modifications as are obvious to those of skill in the art.
Claims (11)
1. A capacitive pressure sensor comprising:
a conductive silicon diaphragm having at least at one side thereof a thick peripheral supporting portion and a thin deflecting portion which may be deflected depending on the pressure applied thereto, said thin deflecting portion being surrounded by said thick peripheral supporting portion so as to form a hollow at said one side of said diaphragm;
a substrate of borosilicate glass having an aperture formed therein and at least a flat side face disposed against said one side of said conductive silicon diaphragm so that said hollow of said diaphragm and said flat side face of said substrate form a pressure chamber into which a fluid under pressure to be detected may be supplied through the aperture; and
at least a conductive thin layer provided on a portion of said flat side face of said substrate in said pressure chamber so as to be opposed to said diaphragm thereby forming electrostatic capacity between said conductive thin layer and said conductive silicon diaphragm;
said conductive silicon diaphragm and said substrate being rigidly joined by a process of anodic bonding to seal said pressure chamber, said joining including said thick supporting portion of said diaphragm and a portion of said substrate.
2. The capacitive pressure sensor as defined in claim 1, wherein said thin deflecting portion of said silicon diaphragm is reduced symmetrically from both sides of said thick peripheral supporting portion to form hollows on both sides of said diaphragm.
3. The capacitive pressure sensor as defined in claim 2, further including a second substrate of borosilicate glass with a flat side face; a thin film electrode provided on the flat side face of said second substrate, said second substrate being disposed against the other side of said silicon diaphragm in contact with said thin peripheral supporting portion of said silicon diaphragm so that a pair of pressure chambers are formed at respective sides of said silicon diaphragm; and joining means joining said second substrate to said silicon diaphragm by anodic bonding.
4. A capacitive pressure sensor comprising:
a conductive silicon diaphragm having a thick peripheral supporting portion, a thin deflecting portion surrounded by said supporting portion, and a rigid movable portion surrounded by said thin deflecting portion;
a substrate of borosilicate glass having an aperture formed therein and being disposed on said thick peripheral supporting portion of said diaphragm so as to form a pressure chamber; and
a thin film electrode disposed on one side of said substrate in said pressure chamber thereby to provide electrostatic capacity between said thin film electrode and said rigid movable portion of said diaphragm;
said conductive silicon diaphragm being joined to said substrate by a process of anodic bonding.
5. The capacitive pressure sensor as defined in claim 4, wherein said rigid movable portion is flat.
6. The capacitive pressure sensor as defined in claims 4 or 5, wherein said thin deflecting portion is annular.
7. A capacitive pressure sensor comprising:
a conductive silicon diaphragm having a thick supporting portion and a thin deflecting portion which may be deflected depending on the pressure applied thereto;
a spacer of borosilicate glass having a pair of parallel plane surfaces; and
a substrate of conductive silicon having an aperture formed therein and being disposed on said thick supporting portion of said diaphragm with said spacer interposed therebetween, thereby forming a pressure chamber between said diaphragm and said substrate into which a fluid may be supplied through said aperture of said substrate, the spacing between said substrate and said diaphragm forming electrostatic capacity therebetween;
said conductive silicon diaphragm, said spacer, and said substrate being joined by a process of anodic bonding.
8. The capacitive pressure sensor as defined in claim 7, wherein said conductive silicon diaphragm has a thick movable portion in the central portion thereof, and said thin deflecting portion of said conductive silicon diaphragm is formed between said thick supporting portion and said thick movable portion so that said conductive silicon diaphragm will be deformed only at said thin deflecting portion.
9. The capacitive pressure sensor as defined in claim 8, wherein said thin deflecting portion of said conductive silicon diaphragm is reduced symmetrically in thickness from said thick supporting portion to said thin electrode portion.
10. The capacitive pressure sensor as defined in claim 9, wherein at both sides of said conductive silicon diaphragm, a pair of said pressure chambers are provided each of which is defined by said conductive silicon diaphragm and said substrate for forming electrostatic capacity.
11. The capacitive pressure sensor as defined in claims 1, 4 or 7, wherein said thin deflecting portion of said diaphragm is formed by an etching process.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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JP53/88450 | 1978-07-21 | ||
JP8845078A JPS5516228A (en) | 1978-07-21 | 1978-07-21 | Capacity type sensor |
Publications (1)
Publication Number | Publication Date |
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US4257274A true US4257274A (en) | 1981-03-24 |
Family
ID=13943129
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US06/059,552 Expired - Lifetime US4257274A (en) | 1978-07-21 | 1979-07-23 | Capacitive pressure sensor |
Country Status (5)
Country | Link |
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US (1) | US4257274A (en) |
EP (2) | EP0059488B1 (en) |
JP (1) | JPS5516228A (en) |
CA (1) | CA1112470A (en) |
DE (2) | DE2966705D1 (en) |
Cited By (62)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3128032A1 (en) * | 1981-07-16 | 1983-02-03 | Robert Bosch Gmbh, 7000 Stuttgart | ARRANGEMENT FOR DETECTING A PRESSURE |
EP0074176A1 (en) * | 1981-08-26 | 1983-03-16 | Leeds & Northrup Company | Variable capacitance pressure transducer |
US4388833A (en) * | 1980-01-07 | 1983-06-21 | Kabushiki Kaisha Hokushin Denki Seisakusho | Differential pressure gauge |
EP0097339A2 (en) * | 1982-06-18 | 1984-01-04 | General Signal Corporation | Multiple range capacitive pressure transducer |
US4527428A (en) * | 1982-12-30 | 1985-07-09 | Hitachi, Ltd. | Semiconductor pressure transducer |
US4536820A (en) * | 1984-03-29 | 1985-08-20 | General Signal Corporation | Electrical feedthrough means for pressure transducer |
US4542435A (en) * | 1984-03-29 | 1985-09-17 | General Signal Corporation | Pressure transducer and mounting |
EP0157599A2 (en) * | 1984-03-29 | 1985-10-09 | General Signal Corporation | Pressure transducer |
DE3520064A1 (en) * | 1984-06-07 | 1985-12-12 | Vaisala Oy, Helsinki | CAPACITIVE PRESSURE SENSOR AND METHOD FOR THE PRODUCTION THEREOF |
US4565096A (en) * | 1983-12-09 | 1986-01-21 | Rosemount Inc. | Pressure transducer |
US4572000A (en) * | 1983-12-09 | 1986-02-25 | Rosemount Inc. | Pressure sensor with a substantially flat overpressure stop for the measuring diaphragm |
US4589054A (en) * | 1984-02-21 | 1986-05-13 | Vaisala Oy | Capacitive pressure detector independent of temperature |
US4594639A (en) * | 1984-02-21 | 1986-06-10 | Vaisala Oy | Capacitive pressure detector |
US4628403A (en) * | 1984-02-21 | 1986-12-09 | Vaisala Oy | Capacitive detector for absolute pressure |
US4769738A (en) * | 1986-12-12 | 1988-09-06 | Fuji Electric Co., Ltd. | Electrostatic capacitive pressure sensor |
DE3814109A1 (en) * | 1987-05-08 | 1988-11-24 | Vaisala Oy | CAPACITOR ARRANGEMENT FOR USE IN PRESSURE SENSORS |
DE3737059A1 (en) * | 1987-10-29 | 1989-05-11 | Siemens Ag | Measurement converter with a capacitative sensor |
US4862317A (en) * | 1987-05-08 | 1989-08-29 | Vaisala Oy | Capacitive pressure transducer |
US4875368A (en) * | 1987-09-08 | 1989-10-24 | Panex Corporation | Pressure sensor system |
US4875369A (en) * | 1987-09-08 | 1989-10-24 | Panex Corporation | Pressure sensor system |
US4879627A (en) * | 1988-12-30 | 1989-11-07 | United Technologies Corporation | Differential capacitive pressure sensor with over-pressure protection |
US4905575A (en) * | 1988-10-20 | 1990-03-06 | Rosemount Inc. | Solid state differential pressure sensor with overpressure stop and free edge construction |
US4996627A (en) * | 1989-01-30 | 1991-02-26 | Dresser Industries, Inc. | High sensitivity miniature pressure transducer |
DE4224524A1 (en) * | 1991-07-26 | 1993-01-28 | Fuji Electric Co Ltd | ELECTROSTATIC CAPACITY TYPE DIFFERENTIAL PRESSURE DETECTOR |
DE4207949C1 (en) * | 1992-03-10 | 1993-04-01 | Mannesmann Ag, 4000 Duesseldorf, De | Capacitative differential pressure sensor of glass-silicon@ type - has second pressure supply channel communicating with first but offset in covering plate |
DE4207952C1 (en) * | 1992-03-10 | 1993-04-15 | Mannesmann Ag, 4000 Duesseldorf, De | Capacitative differential pressure sensor for simple mfr. - comprises silicon diaphragm with edges having thinned areas, leaving central area, pressure input channels aligned with thickened edge region, and flat recesses |
DE4207950C1 (en) * | 1992-03-10 | 1993-05-13 | Mannesmann Ag, 4000 Duesseldorf, De | Capacitative differential pressure sensor - has two carrier plates of monocrystalline silicon@ with flat recesses etched to form measuring chamber by facing diaphragm plate of boron silicate glass |
WO1993026040A1 (en) * | 1992-06-17 | 1993-12-23 | Mannesmann Kienzle Gmbh | Method and device for stacking substrates which are to be joined by bonding |
US5273939A (en) * | 1991-03-09 | 1993-12-28 | Robert Bosch Gmbh | Method of assembling micromechanical sensors |
US5381300A (en) * | 1992-02-20 | 1995-01-10 | Sextant Avionique | Capacitive micro-sensor with a low stray capacity and manufacturing method |
US5479827A (en) * | 1994-10-07 | 1996-01-02 | Yamatake-Honeywell Co., Ltd. | Capacitive pressure sensor isolating electrodes from external environment |
DE4446703A1 (en) * | 1994-12-12 | 1996-06-13 | Mannesmann Ag | Bond interface for joining partly metallised glass or ceramic substrate |
US5531128A (en) * | 1993-08-20 | 1996-07-02 | Vaisala Oy | Capacitive transducer feedback-controlled by means of electrostatic force and method for controlling the profile of the transducing element in the transducer |
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US7043960B1 (en) * | 2004-06-17 | 2006-05-16 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Self-calibrating pressure transducer |
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JPS5887880A (en) * | 1981-11-20 | 1983-05-25 | Hitachi Ltd | Semiconductor diaphragm type sensor |
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US4533795A (en) * | 1983-07-07 | 1985-08-06 | American Telephone And Telegraph | Integrated electroacoustic transducer |
US4467394A (en) * | 1983-08-29 | 1984-08-21 | United Technologies Corporation | Three plate silicon-glass-silicon capacitive pressure transducer |
JPS6085568A (en) * | 1983-10-18 | 1985-05-15 | Toyota Central Res & Dev Lab Inc | Electrostatic junction |
JPS60138434A (en) * | 1983-12-27 | 1985-07-23 | Fuji Electric Co Ltd | Manufacture of semiconductor electrostatic capacity type pressure sensor |
JPS60233863A (en) * | 1984-05-04 | 1985-11-20 | Fuji Electric Co Ltd | Pressure sensor of electrostatic capacitance type |
EP0167941A3 (en) * | 1984-07-09 | 1988-10-05 | Siemens Aktiengesellschaft | Differential pressure gauge head |
US4689999A (en) * | 1985-07-26 | 1987-09-01 | The Garrett Corporation | Temperature compensated pressure transducer |
DE3625411A1 (en) * | 1986-07-26 | 1988-02-04 | Messerschmitt Boelkow Blohm | CAPACITIVE ACCELERATION SENSOR |
JPH061228B2 (en) * | 1987-08-13 | 1994-01-05 | 富士電機株式会社 | Capacitive pressure detector |
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JP2570420B2 (en) * | 1988-06-23 | 1997-01-08 | 富士電機株式会社 | Capacitive pressure detector |
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JP2639159B2 (en) * | 1989-04-14 | 1997-08-06 | 富士電機株式会社 | Capacitive differential pressure detector |
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US4388833A (en) * | 1980-01-07 | 1983-06-21 | Kabushiki Kaisha Hokushin Denki Seisakusho | Differential pressure gauge |
US4475402A (en) * | 1981-07-16 | 1984-10-09 | Robert Bosch Gmbh | Pressure sensing apparatus |
DE3128032A1 (en) * | 1981-07-16 | 1983-02-03 | Robert Bosch Gmbh, 7000 Stuttgart | ARRANGEMENT FOR DETECTING A PRESSURE |
EP0074176A1 (en) * | 1981-08-26 | 1983-03-16 | Leeds & Northrup Company | Variable capacitance pressure transducer |
US4390925A (en) * | 1981-08-26 | 1983-06-28 | Leeds & Northrup Company | Multiple-cavity variable capacitance pressure transducer |
EP0097339A2 (en) * | 1982-06-18 | 1984-01-04 | General Signal Corporation | Multiple range capacitive pressure transducer |
US4445383A (en) * | 1982-06-18 | 1984-05-01 | General Signal Corporation | Multiple range capacitive pressure transducer |
EP0097339A3 (en) * | 1982-06-18 | 1984-10-10 | General Signal Corporation | Multiple range capacitive pressure transducer |
US4527428A (en) * | 1982-12-30 | 1985-07-09 | Hitachi, Ltd. | Semiconductor pressure transducer |
US4565096A (en) * | 1983-12-09 | 1986-01-21 | Rosemount Inc. | Pressure transducer |
US4572000A (en) * | 1983-12-09 | 1986-02-25 | Rosemount Inc. | Pressure sensor with a substantially flat overpressure stop for the measuring diaphragm |
US4628403A (en) * | 1984-02-21 | 1986-12-09 | Vaisala Oy | Capacitive detector for absolute pressure |
US4589054A (en) * | 1984-02-21 | 1986-05-13 | Vaisala Oy | Capacitive pressure detector independent of temperature |
US4594639A (en) * | 1984-02-21 | 1986-06-10 | Vaisala Oy | Capacitive pressure detector |
EP0157599A2 (en) * | 1984-03-29 | 1985-10-09 | General Signal Corporation | Pressure transducer |
US4542435A (en) * | 1984-03-29 | 1985-09-17 | General Signal Corporation | Pressure transducer and mounting |
US4536820A (en) * | 1984-03-29 | 1985-08-20 | General Signal Corporation | Electrical feedthrough means for pressure transducer |
EP0157599A3 (en) * | 1984-03-29 | 1987-03-18 | General Signal Corporation | Pressure transducer and mounting |
DE3520064A1 (en) * | 1984-06-07 | 1985-12-12 | Vaisala Oy, Helsinki | CAPACITIVE PRESSURE SENSOR AND METHOD FOR THE PRODUCTION THEREOF |
US4597027A (en) * | 1984-06-07 | 1986-06-24 | Vaisala Oy | Capacitive pressure detector structure and method for manufacturing same |
US4769738A (en) * | 1986-12-12 | 1988-09-06 | Fuji Electric Co., Ltd. | Electrostatic capacitive pressure sensor |
DE3814109A1 (en) * | 1987-05-08 | 1988-11-24 | Vaisala Oy | CAPACITOR ARRANGEMENT FOR USE IN PRESSURE SENSORS |
US4831492A (en) * | 1987-05-08 | 1989-05-16 | Vaisala Oy | Capacitor construction for use in pressure transducers |
US4862317A (en) * | 1987-05-08 | 1989-08-29 | Vaisala Oy | Capacitive pressure transducer |
US4875369A (en) * | 1987-09-08 | 1989-10-24 | Panex Corporation | Pressure sensor system |
US4875368A (en) * | 1987-09-08 | 1989-10-24 | Panex Corporation | Pressure sensor system |
DE3737059A1 (en) * | 1987-10-29 | 1989-05-11 | Siemens Ag | Measurement converter with a capacitative sensor |
US4905575A (en) * | 1988-10-20 | 1990-03-06 | Rosemount Inc. | Solid state differential pressure sensor with overpressure stop and free edge construction |
US4879627A (en) * | 1988-12-30 | 1989-11-07 | United Technologies Corporation | Differential capacitive pressure sensor with over-pressure protection |
US4996627A (en) * | 1989-01-30 | 1991-02-26 | Dresser Industries, Inc. | High sensitivity miniature pressure transducer |
US5273939A (en) * | 1991-03-09 | 1993-12-28 | Robert Bosch Gmbh | Method of assembling micromechanical sensors |
DE4224524A1 (en) * | 1991-07-26 | 1993-01-28 | Fuji Electric Co Ltd | ELECTROSTATIC CAPACITY TYPE DIFFERENTIAL PRESSURE DETECTOR |
US5381300A (en) * | 1992-02-20 | 1995-01-10 | Sextant Avionique | Capacitive micro-sensor with a low stray capacity and manufacturing method |
DE4207950C1 (en) * | 1992-03-10 | 1993-05-13 | Mannesmann Ag, 4000 Duesseldorf, De | Capacitative differential pressure sensor - has two carrier plates of monocrystalline silicon@ with flat recesses etched to form measuring chamber by facing diaphragm plate of boron silicate glass |
DE4207952C1 (en) * | 1992-03-10 | 1993-04-15 | Mannesmann Ag, 4000 Duesseldorf, De | Capacitative differential pressure sensor for simple mfr. - comprises silicon diaphragm with edges having thinned areas, leaving central area, pressure input channels aligned with thickened edge region, and flat recesses |
DE4207949C1 (en) * | 1992-03-10 | 1993-04-01 | Mannesmann Ag, 4000 Duesseldorf, De | Capacitative differential pressure sensor of glass-silicon@ type - has second pressure supply channel communicating with first but offset in covering plate |
WO1993026040A1 (en) * | 1992-06-17 | 1993-12-23 | Mannesmann Kienzle Gmbh | Method and device for stacking substrates which are to be joined by bonding |
US6168678B1 (en) | 1992-06-17 | 2001-01-02 | Mannesmann Kienzle Gmbh | Method and device for stacking substrates which are to be joined by bonding |
US5656781A (en) * | 1993-07-07 | 1997-08-12 | Vaisala Oy | Capacitive pressure transducer structure with a sealed vacuum chamber formed by two bonded silicon wafers |
US5531128A (en) * | 1993-08-20 | 1996-07-02 | Vaisala Oy | Capacitive transducer feedback-controlled by means of electrostatic force and method for controlling the profile of the transducing element in the transducer |
US5479827A (en) * | 1994-10-07 | 1996-01-02 | Yamatake-Honeywell Co., Ltd. | Capacitive pressure sensor isolating electrodes from external environment |
DE4446703A1 (en) * | 1994-12-12 | 1996-06-13 | Mannesmann Ag | Bond interface for joining partly metallised glass or ceramic substrate |
US6484585B1 (en) | 1995-02-28 | 2002-11-26 | Rosemount Inc. | Pressure sensor for a pressure transmitter |
US6089097A (en) * | 1995-02-28 | 2000-07-18 | Rosemount Inc. | Elongated pressure sensor for a pressure transmitter |
US6079276A (en) * | 1995-02-28 | 2000-06-27 | Rosemount Inc. | Sintered pressure sensor for a pressure transmitter |
US6082199A (en) * | 1995-02-28 | 2000-07-04 | Rosemount Inc. | Pressure sensor cavity etched with hot POCL3 gas |
US5663506A (en) * | 1995-08-21 | 1997-09-02 | Moore Products Co. | Capacitive temperature and pressure transducer |
US5804736A (en) * | 1996-06-11 | 1998-09-08 | Moore Products Co. | Differential capacitive transducer |
US6029524A (en) * | 1996-06-11 | 2000-02-29 | Moore Products Co. | Transducer having redundant pressure sensors |
US5672808A (en) * | 1996-06-11 | 1997-09-30 | Moore Products Co. | Transducer having redundant pressure sensors |
US6156585A (en) * | 1998-02-02 | 2000-12-05 | Motorola, Inc. | Semiconductor component and method of manufacture |
US6426239B1 (en) | 1998-02-02 | 2002-07-30 | Motorola, Inc. | Method of manufacturing a semiconductor component having a fixed electrode between two flexible diaphragms |
DE19902450A1 (en) * | 1999-01-22 | 2000-08-03 | Festo Ag & Co | Miniaturized electronic system has chip and carrier mechanically and electrically connected by direct chip bonding using flip-chip technology via annular bond seal(s) and contact bump(s) |
DE19902450B4 (en) * | 1999-01-22 | 2006-04-20 | Festo Ag & Co. | Miniaturized electronic system and method suitable for its production |
US6561038B2 (en) | 2000-01-06 | 2003-05-13 | Rosemount Inc. | Sensor with fluid isolation barrier |
US6516671B2 (en) | 2000-01-06 | 2003-02-11 | Rosemount Inc. | Grain growth of electrical interconnection for microelectromechanical systems (MEMS) |
US6520020B1 (en) | 2000-01-06 | 2003-02-18 | Rosemount Inc. | Method and apparatus for a direct bonded isolated pressure sensor |
US6505516B1 (en) | 2000-01-06 | 2003-01-14 | Rosemount Inc. | Capacitive pressure sensing with moving dielectric |
US6508129B1 (en) | 2000-01-06 | 2003-01-21 | Rosemount Inc. | Pressure sensor capsule with improved isolation |
US6715356B2 (en) * | 2000-02-22 | 2004-04-06 | Peter Gerst | Pressure sensor having metallic diaphragm seal mount |
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US6581469B2 (en) | 2001-01-12 | 2003-06-24 | Endress + Hauser Gmbh Co. | Differential pressure sensor and method of differential pressure measurement |
US20030209080A1 (en) * | 2002-05-08 | 2003-11-13 | Sittler Fred C. | Pressure sensor assembly |
US6848316B2 (en) | 2002-05-08 | 2005-02-01 | Rosemount Inc. | Pressure sensor assembly |
US7188530B2 (en) | 2002-06-18 | 2007-03-13 | Corporation For National Research Initiatives | Micro-mechanical capacitive inductive sensor for detection of relative or absolute pressure |
US20050103112A1 (en) * | 2002-06-18 | 2005-05-19 | Corporation For National Research Initiatives | Micro-mechanical capacitive inductive sensor for wireless detection of relative or absolute pressure |
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US20080005049A1 (en) * | 2004-03-10 | 2008-01-03 | Wheeler Steven J | Collecting and Processing Data |
US7043960B1 (en) * | 2004-06-17 | 2006-05-16 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Self-calibrating pressure transducer |
US20060179953A1 (en) * | 2005-02-16 | 2006-08-17 | Denso Corporation | Pressure sensing element and sensor incorporating the same |
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Also Published As
Publication number | Publication date |
---|---|
EP0007596A1 (en) | 1980-02-06 |
DE2966705D1 (en) | 1984-03-29 |
CA1112470A (en) | 1981-11-17 |
JPS5516228A (en) | 1980-02-04 |
EP0007596B1 (en) | 1984-02-22 |
EP0059488A1 (en) | 1982-09-08 |
EP0059488B1 (en) | 1984-12-27 |
DE2967341D1 (en) | 1985-02-07 |
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